1. Technical Field
The present invention relates to a method and an apparatus for incinerating refuses and melting ash produced upon an incineration of the refuses.
2. Background Art
Today, various methods of melting refuses at high temperture and solidifying incineration ashes (incineration residue) are known in the art. Such methods have been developed for a reduction of weight and volume of an incineration reside and for a recycling of the refuses.
For an apparatus to carry out such a method, there are, for example, an electric melting furnace as shown in FIG. 5 of the accompanying drawings and a film melting furnace as shown in FIG. 6.
Referring first to FIG. 5, the electric melting furnace 1 is designed to have an incineration ash A fed from a supply port 2 formed at the top of the furnace 1 and melt the ash A with the arc heat produced by electrodes 3 installed in the furnace 1. The ash A is melt to a melt B, which is generally called "molten bath", and the melt B is discharged from an exhaust port 4 formed in a lateral wall of the furnace 1 and then solidified.
Referring to FIG. 6, the film melting furnace 11 is designed to have an inlet 12 through which the incineration ash A is dumped into of the furnace 11, and the ash A is melt to the melt B from the surface 14 of the ash A by flames from the oil burner 13. The melt B is discharged from an outlet 15 formed at the bottom of the furnace 11.
However, the above-mentioned conventional method and apparatus have a disadvangate that a large amount of fuel or electric power is required to melt the ash, thereby raising an operation cost.
The applicant of the present invention proposed a waste disposal method, which is disclosed in Japanese Patent Application No. 62-232646, for example, to eliminate the above-mentioned disadvantage. FIG. 7 shows a schematic view of an apparatus to carry out the improved method. The refuses S are incinerated in a rotary stoker 31 such that the incineration residue (ash) A contains a certain amount of carbon (unburned carbon). The ash A is transferred to the ash melting furnace 33 via an after-burning stoker 32. Combustion air is supplied into the furnace 33 to melt the ash A with the unburned carbon remaining in the ash A.
However, the apparatus of FIG. 7 cannot perform a stable incineration since the amount of unburned carbon contained in the ash A is an important factor for the incinerator but is not controlled, i.e., the method of controlling the unburned carbon is not disclosed in the above-mentioned Japanese Patent Application.